Hydraulic engine mounts are used to position an engine and to control the gross motion of the engine within a vehicle. The hydraulic engine mount also provides damping to absorb energy created by the moving engine by a large amplitude excitation (±1.0 millimeter) and to provide isolation so that vibration of an engine does not transfer to the vehicle structure by small amplitude excitation (±0.1 millimeter). As shown in FIG. 1, previously known engine mounts include an upper mounted housing and a lower housing. A threaded stud for mounting the engine extends from the top of the housing. The threaded stud is inserted into a threaded aperture of a core. The core is molded to a main rubber element, thereby defining a main component of the main rubber element. The main rubber element is formed by the upper core, highly elastic rubber, and the outer, all separate and distinct and later molded together. The outer ring rests on top of the lower housing. When the top of the mount is moved due to large amplitude excitation of the engine, the fluid in the inertia track is pumped back and forth from the upper chamber to the lower chamber through the inertia track. The size of the inertia track is tuned so that the fluid in the track will provide maximum damping at a particular frequency determined by the application. The highly elastic rubber, along with a decoupler, contributes to good isolation characteristics. The decoupler is a rubber disk that is captured between the top and bottom inertia track planes. The disk provides compliance as the fluid in the working chamber acts upon it, thus keeping the pressure from building up in the walls of the main rubber element, keeping the mount stiffness low.
The hydraulic engine mount is usually made with a softer rubber compared to conventional engine mounts to thereby provide good isolation at low amplitude (idle, smooth road) and the fluid in the upper chamber provides damping at the high amplitude situations (speed bumps, potholes, and shifting gears).
The outer ring rests on top of the lower housing and provides a seal to prevent fluid from escaping from the upper chamber, the lower chamber or outside of the hydraulic engine mount. Traditionally, the main rubber element and the outer ring are separate and distinct elements. The outer ring requires extensive pre-installation procedures including cleaning, pretreatments, and coatings with special adhesives. Additionally, the outer ring increases complication of assembly to ensure the outer ring is properly sealed. Accordingly, it is advantageous to provide an improved outer ring or an improved main rubber element having improved sealing features as well as simplified installation procedures.